We looked at answers to questions in the General Social Survey, a nationally representative survey of Americans conducted every year or two since 1972, yielding responses from more than 30,000 Americans. We were interested in changes over time in reports of same-sex sexual behavior and attitudes about same-sex sexual behavior.

The survey asks people how they feel about “sexual relations between two adults of the same sex,” with possible answers of “always wrong,” “almost always wrong,” “wrong only sometimes,” and “not wrong at all.” The survey began asking this question in 1973, when only 11 percent of Americans believed that same-sex sexual behavior was “not wrong at all.” That number barely changed through the 1980s but began to climb steadily in the 1990s. Today, 49 percent of Americans believe that same-sex sexual relations are “not wrong at all,” and 63 percent of young Americans (often dubbed millennials) report this highest level of acceptance. That’s a huge increase in just 25 years!